Flexible tubing.



R. & W. P. ABELL.

FLEXIBLE TUBING.

APPLICATION FILED SEPT. 18, 1912.

Patented July 29, 1913.

UNITED STATES PATENT OFFICE.

ROLLIN ABELL, OF MILTON, AND WALTER P. ABELL, 0F QUINCY, MASSACHUSETTS.

FLEXIBLE ,TU'BING.

ble Tubing, of which the following is a specification. v

v This invention relates to flexible tubing made of a metal stripwound in the form of a helix, the strip being provided with ribs and grooves whereby the several convolu-' tions are interlocked one with another to prevent separation but at the same time to permit limited flexure of the'tubing.

The invention consists in the relative. Width and thickness of the several parts of the strip, whereby greater strength is obtained without increasing the thicknes s'ot the strip, or, conversely, whereby the thickness of the strip may .be redueed 'without decreasing the strength of the tubing.

- Ofxthe accompanying; drawings which illustrate the. invention: gure 1 represents a side elevation of a short piece of tubing, a

. portion of'which is broken awayto expose the relation in which the convolutions of the strip are interlocked with each other. Fig.

2 represents a perspective View of 'a short piece of a strip before the same wound into the form of a tube. Fig. 3 represents a cross section, on a larger scale, of the strip, the dotted lines representing other convolutions of the strip interlocked therewith inthe relation which the convolutions of the tubing occupy. Fig. 4 represents a cross section of a strip o which the thickness of metal is uniform at all points, this l'or'nrol" strip having none o.l' the l'ruturos of the present inventiion but being illustrated solely for the sake f (.toinparison. Fig. 5 represents a cross section of: a distorted strip such asthat shown by Fig. 4, the abnormal shape representing the result which the present in'-- vention is intended to avoid. Fig. (3 represents a cross section of a strip similar to that.

shown by Fig. 4, but larger. Fig. 7 representsa cross section of two llll'tblluflked portions of a strip which. has undercut flanges.

The same reference characters indicate the.

same parts wherever they occur.

The strip which forms the snlncot-matter l: the present invention and which is illus- Specification of Letters Patent. Application filed September 18, 1912.

.that of the body portion.

'tubes lengt bending the tube until all lost motion be- .of the strain.

Serial No. 720,965.

trated by Figs. 1, 2 and-3, is composed of Patented July 29, 1913.

ductile met-alandcomprises a central longitudinal body portion 10, marginal flanges 11, and webs 12 each of which connects one- .of the flanges with the body portioni The relative proportions of the several parts of the'stri are shown best b Fig. 3. For the sake 0 description the epth'of the strip will be regarded as the distance from top to bottom, or, in other words, the distance between the surfaces indicated by lines a, a.

The depth of the body portion 10 is therefore equal to the depth of the strip.- The width of the body portion. is indicatedby lines 12, b, and the width of the entire strip is lndicated'by lines 0, c. It' will be observed that the depth of the flanges 11 is less than that of the body I portion, and that the width of the flanges 18 i kewise lessthan It will also be observed that the depth of the webs 12 is less than every other measurement of; the

strip. The reatest strain to which tubing of this kind is ordinarily subjected is-tensile strain. This strain may be the result of a mere pullinglstra-inin the direction of the or it may be the re'sulto'f tween the convolutions is taken up. When the tube is bent so far as to take up all lostmoti'on and is subjected to further bending stress, the tensile strain occurs at the outer away from each other and to distort the v body portion. Theresult of suchst ress upon a strip such'as' that shown byfFig. ,4 is represented by Fig. 5, the direction of stress being represented by arrows upon the flanges. body portion of the strip shown by Figs. 4;

and 5 is indicated at 10*, the flanges are .l' or the sake of. comparison, the' indicated at 11", and the connecting webs at I25 The thickness of the metal throughout these dilfcrent portions is uniform. VVhen' excessive strain is applied as indicated by the arrows 'on the strip, the body pln'tion and the flanges become bentas shown by .l ig. 5, because they are subjected-to leveiaige due to their angles, and these portions tend.

to assume positions in line with the direction As between the body portion and the flanges, the former is the first to yield because of, the greater disadvantage due to itsgreat r depth. Whenthematerial along the outer; side of. the bent tube-is disthe disadvantages due to levers. e and to the greatest depth. The width oft e flanges 11 is also made greater than the depth of the webs, for the same reason; but the width of the flanges does not need to be asgreat as the width of the body portion, because the depth of the flanges is not so great as the depth of the body portion and consequently the leverage to which the flanges are subjected is not-so great as the leverage to which the body portion is subjected. The

proportions of the improved strip are de-' signed with the purpose of rendering the strip substantially uniform with regard to its ability to withstand the unequal strains at the different points, to the end that there may he no unnecessary material at any point, because the resence of unnecessary material increases tie difliculty of winding the strip and renders the tubing undesirably bulky.

. The improved strip is in one sense a combination of the strips shown by Figs. 4 and 6 in that its thinnest parts are-equal to the thickness of the metal in .Fig. 4, while its body portion has the same width as the metal in the strip shown by Fig. 6. The depth of the strip shown by Fig. 3 is no greater than the depth of that shown by Fig. 4, and there is no more weight or bulk in the tubing, and yet the strip shown by Fig. 3 has greater width and greater strength than the form shown by Fig. 4.- The ability of the strip shown by Fig. 3 to withstand lateral strain is even greater than that'of the strip shown by Fig. 6, notwithstanding the greater bulk of metal in the latter figure. The thicker webs of Fig. 6 are of no advantage because there isno bending strain applied to them. This excessive thickness is undesirable, first,.because itrenders Windingtoo diflicult, sec- 0nd, it unduly limits the minimum diameter of the tubing, and third, it renders the tubingtoo bulky. Thesuperior strength of the form. shown by Fig. 3 is due to the fact that the depth of the body portion is less than the depth of the body portion" in Fig;

6, while the width of that portion is the same. The leverage to which the body portion of Fig. 3 is subjected is less than the leverage to which that of Fig. 6'wou1d be -trans'v'ersely of the strip. r The relatively greater width of the body" subjected when tensile ams applied the matter of roportions" of the several parts, but is di erent in that the cimtiguoas faces 14 of the flanges are undercut. Assn, incident to this arrangement of the faces is:

the other faces which extend from the top to the bottom of the strip areinclined to the same degree so as to facilitate the insertion of the flanges into the grooves. The purpose in arran'gin the faces 14: as de-' scribed isf'to hold t e convoiutions interlocked in case the flanges are slightlyflexed by tensile strain transverse with relation to the length of the st-rip.: There isg of course, {a possibility oi slight flexure of the flan when the tubing'is subjected to great tensile strain, and when the contacting faces of the flanges are normally at right angles to the and 3, these faces would be slightly inclined portion and of the flanges inqthe improved same as that shown by Figs. 1,2 in

length of the tubing, as shown by Figs. 1, 2

in suchinanner as to aflord tendency of the I i flanges to slip oii' each other, and it is in order to counteract this tendenc that the faces 14 are inclined as shown y Fig. .The term undercut as applied to the faces 14 pertains to their condition rather than the method by which they are formed.

The strip is preferably formed by being drawn through a die or through a series of dies instead of being passed between rolls.

The reason for this preference is that the.

corners of the strip, as indicated at 13, may be formed more sharply by drawing than by able because they afi'ord smoother surfaces upon the interior and exterior of fins. our:

ished. tubing, by lessening the width of the grooves between the convolutionsi It is not intended, however, to'limit the invention to a drawn metal strip, because for some par-f poses a rolled strip having the desired characteristics may serveas well.

We claim: x 1. A flexible tube consisting of ahelieal strip of metal, said strip havin a body'portion, marginal flanges, and we connecting said flanges with the body portion, as can rolling; and the sharper corners are desir tion, marginal flanges, and wev connecting 2. A flexible tube consisting of a strip of metal, said strip havin a body pain" volutions being movably interlocked with In testimony whereof WU have aliixed our ezu-h other by said flanges and being capable E signatures, in presence of two Witnesses.

of relative movement longitudinally of the ROLLIN ABELL.

tube, said body ortion being relatively WALTER P. ABELL.

wide, said flanges eing narrower than the Vitnesses: body portion, and said webs being thinner JOHN E. POVEY, than thewidth of said flanges. MARY A. HINES. 

